This invention relates, in general, to semiconductor devices, and more particularly, to a self-aligned field effect transistor having a highly non-linear transfer characteristic.
Semiconductor devices that have non-linear current-voltage characteristics allow greater functionality to be incorporated into smaller devices. Such devices are referred to herein as "multi-functional" devices. In recent years, a few multi-functional devices have been developed. Examples of such devices include Esaki diodes and resonant tunneling diodes. Most of these devices take advantage of the negative differential resistance that is caused by resonant tunneling of electrons.
Even more useful for digital logic applications than non-linear diodes would be non-linear three terminal devices which provide gain. Resonant tunneling hot electron transistors and bipolar resonant tunneling transistors, are examples of currently available three terminal devices. Even though these devices show some nonlinear characteristics, the observed non-linearitites are small at room temperature and the performance improves at liquid nitrogen temperatures or below. Currently available devices also have bipolar transistor characteristics with very complicated and nonplanar processes, and consume high standby power.
What is needed is a room temperature field effect transistor with highly nonlinear current-voltage characteristics that consumes low power.